Search PubMed⌕ Search

Biomedical subjects

M Elia

Publications and source records attributed to M Elia.

At least 73 records · Page 4Linked to original sources
PubMed2000

Assessment of body volume using three-dimensional photonic scanning.

Measurement of body volume (BV) can be used to estimate body composition using two- or multicomponent models. The traditional approach, underwater weighing (UWW), is awkward and unsuitable for many subjects. A newer alternative, whole body air displacement plethysmography (ADP), is less demanding but still unsuitable for young children, who may not remain still during the measurement. We have, therefore, considered whether a novel approach, three-dimensional photonic scanning, is a viable alternative. Duplicate measurements of body volume were obtained in 22 adults (11 of each sex; mean [SD] BMI, 21.8 [2.5] kg/m2) by UWW, ADP, and a Hamamatsu Bodyline Scanner (HBS) (Hamamatsu, Japan). Subjects wore a tight-fitting swimming costume for all three measurements, which were performed within one day of each other. Scans lasted 10 seconds, with the subject standing in a predefined position. The body surface skin was reconstructed using a B-spline-fitting model. In UWW, lung volume (LV) was measured simultaneously with underwater weight. In ADP and HBS, LV was predicted from weight and height. Results were compared using correlation and Bland and Altman analysis. Correlation analysis indicated that the scanner successfully ranked subjects in terms of BV. However, Bland and Altman analysis demonstrated that, relative to both UWW and ADP, HBS measured BV without bias but with limits of agreement between individuals of > 2 liters, equivalent to approximately 20% fat. Scan precision was 0.57 liter, or 4.1% fat. Although HBS cannot yet measure BV with sufficient accuracy to predict fatness, much of the error is probably due to difficulties in standardizing LV during the scan. Simultaneous measurement of LV with volume by HBS is expected to improve limits of agreement substantially. Occlusion is also an important source of error. The method offers many advantages over alternative techniques, because the measurement is brief, noninvasive, and suitable for repeat measurements.

Adolescent↗
PubMed2000

Modeling leg sections by bioelectrical impedance analysis, dual-energy X-ray absorptiometry, and anthropometry: assessing segmental muscle volume using magnetic resonance imaging as a reference.

This study aimed to assess the value of different DXA and BIA models for predicting muscle volume in mid-thigh segments obtained by MRI. Three DXA models were used: in model A, muscle was taken to be equivalent to fat-free soft tissue; in model B the thigh segment was divided into its constituent tissues using fixed assumptions about tissue composition; in model C the assumptions were similar to model B, but with variable distribution of fat and fat-free soft tissue, depending on body mass index. The two BIA models (both parallel tissue resistance models) involved impedance measurements at 50 kHz, and assumptions about either the specific resistivities of all the constituent tissues (model A), or resistivities of only adipose tissue and muscle (model B). Anthropometric estimates (thigh circumference and skinfold thickness) assumed that both limb and muscle circumference were circular. Compared to MRI estimates of muscle mass, those obtained by DXA model A (fat-free soft tissue) were not as good as those obtained using models B and C, although the standard deviations of the differences were similar with all three models. The BIA models were superior to the anthropometric estimates of muscle volume (relative to MRI) with respect to bias, but the standard deviations of the differences were large for both. The intraobserver repeatabilities for muscle volume were < 0.5% for MRI, < 1% for DXA, 1.8% for BIA, and 1.7% for anthropometry (interobserver value for BIA was 3.8% and for anthropometry 3.5%). The study suggests that DXA modeling provides a promising approach for assessing muscle mass in thigh segments, and suggests the potential value of parallel BIA models for groups of individuals but not for individual subjects, possibly because muscle resistivity is influenced not only by its composition but also by the direction of current flow in muscle.

Absorptiometry, Photon↗
PubMed2000

Whole body air displacement plethysmography compared with hydrodensitometry for body composition analysis.

AIMS: To assess the acceptability and feasibility of whole body air displacement plethysmography in children and to determine its precision and agreement with hydrodensitometry, an appropriate reference method. METHODS: Age specific two component model equations were used to predict fat mass from body density in 22 children aged 8-12 years and in 10 adults for comparison of methods. Precision for each method was established from duplicate measurements. RESULTS: Plethysmography was accepted more readily than hydrodensitometry (100% v 69% provided duplicate measurements). Precision for fat mass in children was 0.38 kg by plethysmography and 0.68 kg by hydrodensitometry, and results were similar in adults. The mean (SD) fat mass in children was 6.9 kg (4.0) and 6.7 kg (4. 2) by plethysmography and hydrodensitometry, respectively, but 95% limits of agreement between methods were large (-4.1 kg to 3.5 kg fat). CONCLUSION: Plethysmography was more readily accepted and had better precision than hydrodensitometry. It also provided similar body composition results for the group but not for all individual children.

Adipose Tissue↗
PubMed2000

Clinical correlates of brain morphometric features of subjects with low-functioning autistic disorder.

Numerous neuropathologic and imaging studies have reported different structural abnormalities in the brains of autistic subjects. However, whether or not the degree of brain abnormality is correlated with the severity of developmental impairment in autistic disorder is still unknown. The midsagittal area of the cerebrum, corpus callosum, midbrain, cerebellar vermis, and vermal lobules VI and VII was measured by means of magnetic resonance imaging in 22 boys with low-functioning autistic disorder and in 11 age-matched normal controls. Morphometric measures were statistically compared between groups and correlated with age and scores on the Psychoeducational Profile-Revised and the Childhood Autism Rating Scale. A significant negative correlation was found between midsagittal area of the cerebrum and age in patients with autistic disorder, and a positive correlation was found between the midsagittal area of the midbrain and some subscales of the Psychoeducational Profile-Revised.

Adolescent↗
PubMed2000

Comparison of recoveries in breath carbon dioxide of H13CO-3 and H14CO-3 administered simultaneously by single 6 h constant unprimed intravenous infusion.

The aim of this study was to assess the bioequivalence of H13CO-3 and H14CO-3, by administering both labels simultaneously by single infusion and comparing their recovery in breath CO2 and urinary urea. Six healthy male subjects (age range 24-41 years; weight 76.7 (sd, 18.6) kg; height 1.79 (sd 0.05) m) were infused with unprimed solutions of HCO3- (110.0 mmol/kg) labelled with 13C (0.76 mmol 13C/h) and 14C (48 Bq/h) at a constant rate for 6 h, in a whole-body calorimeter (1400 litres) for measurement of CO2 production. Samples of breath were collected hourly in a Douglas bag and all urine was collected into two batches (0-4 h and 4-6 h) for estimating recovery of infused label by measurement of enrichment or specific activity. Recovery in breath CO2 of both labels increased from about 25 % for the first hour to 88 % and above for hours 3-4 onwards. Mean recovery of 13C in breath CO2 was slightly higher than that of 14C for all periods (mean difference always less than 1 % of infused label) but was significant only for the first 3 h (P < 0.05). Recovery of 14C in urea was significantly higher (P < 0.01) than 13C, but was confounded by substantial variability and uncertainties concerning 13CO2 background enrichments. These results suggest that there is no compelling need to alter factors currently used for recovery of 14C in breath when using 13C instead, and vice versa.

Adult↗
PubMed1999

Sulphation deficit in "low-functioning" autistic children: a pilot study.

BACKGROUND: Parents of autistic children and autism support groups often report that autistic episodes are exacerbated when the children eat certain foodstuffs such as dairy products, chocolates, wheat, corn sugar, apples, and bananas. The hypothesis that autistic behavior might be related to metabolic dysfunctions has led us to investigate in a group of "low functioning" autistic children and in an age-matched control group each made up of 20 subjects, the sulphation capacity available. METHODS: Utilizing the biochemical characteristics of paracetamol we evaluated by high performance liquid chromatography, the urine paracetamol-sulfate/paracetamol-glucuronide (PS/PG) ratio in all subjects following administration of this drug. RESULTS: The PS/PG ratio in the group of autistic subjects gave a significantly lower results than the control group with p < .00002. CONCLUSIONS: The inability to effectively metabolize certain compounds particularly phenolic amines, toxic for the CNS, could exacerbate the wide spectrum of autistic behavior.

Acetaminophen↗
PubMed1999

Short-term growth hormone administration at the time of opportunistic infections in HIV-positive patients.

OBJECTIVES: A 12-week course of recombinant human growth hormone is an effective but expensive therapy for established HIV-related wasting. Wasting in HIV disease is often episodic, coinciding with bouts of acute opportunistic infection. We hypothesized that a short course of growth hormone, targeted at the time of opportunistic infection, might improve protein metabolism thereby reducing lean tissue loss. METHODS: HIV-infected men with acute opportunistic infections, who received standard antimicrobial treatment for their infection as well as intensive nutritional counselling and oral energy supplements, were randomized to receive growth hormone or placebo for 14 days. Principal assessments were protein metabolism (measured by 13C-leucine infusion), body composition (measured by DEXA) and safety. RESULTS: There were no significant changes in outcome parameters in the placebo group (n = 11). In the growth hormone group (n = 9), protein catabolic rate decreased by 60% in the fasted state (P = 0.02 versus placebo), lean body mass increased by 2.2 kg (P = 0.03 versus baseline) and fat mass decreased by 0.7 kg (P = 0.002 versus baseline). There was no increase in adverse or serious adverse events in the growth hormone as compared with the placebo group. CONCLUSIONS: A two-week course of growth hormone at the time of acute opportunistic infection in HIV-infected patients improves protein metabolism and body composition during therapy and appears to be safe. This may represent a rational and economical approach to the use of growth hormone therapy.

AIDS-Related Opportunistic Infections↗
PubMed1999

Impact of tuberculosis on the body composition of HIV-infected men in Brazil.

OBJECTIVE: Tuberculosis (TB) is the commonest HIV-related opportunistic infection in many developing countries and is thought to be a frequent underlying cause of HIV-associated wasting. We have used reference water dilution methods to examine the body composition changes associated with TB and to assess the severity and pattern of wasting. METHODS: The study was conducted at a charitable support house for poor and homeless HIV-infected people in Rio de Janeiro, Brazil. Male patients who were HIV-positive and receiving treatment for active TB (HIVTB+) and HIV-infected controls without TB (HIVTB-) were studied. Total body water (TBW) and extracellular water (ECW) were measured by giving oral doses of deuterium oxide and sodium bromide, respectively, and determining enrichment in plasma after 4 hours. Intracellular water (ICW), body cell mass (BCM), lean body mass (LBM) and fat mass were calculated from these parameters using standard equations. RESULTS: HIVTB+ (n = 11) and HIVTB- (n = 12) groups were similar in age, height, CD4 count and HIV risk factors. HIVTB+ men had significantly lower mean ICW (13.2 versus 16.6 kg; p = .02) and BCM (18.4 versus 23.0 kg; p = .02), a relative expansion of ECW (35.0 versus 30.0 L/kg body weight; p = .04), and small and nonsignificant reductions in total body weight (58.0 versus 62.1 kg; p = .26), LBM (45.5 versus 47.7 kg; p = .33) and fat mass (12.5 versus 14.4 kg; p = .51) compared with HIVTB- controls. BCM in the HIVTB+ group was similar to reference values for severe malnutrition. The relative depletion of BCM appeared excessive in comparison with reference values for uncomplicated starvation. CONCLUSION: The nutritional status of HIVTB+ patients was significantly worse than HIVTB- patients. Body weight and LBM underestimated the nutritional deficit, and measurement of BCM is therefore necessary to appreciate the extent of malnutrition in such patients. Malnutrition in HIVTB+ patients is severe and may therefore contribute to decreased survival. Hypermetabolism appears to play a role in the wasting process in patients coinfected with HIV and TB.

AIDS-Related Opportunistic Infections↗
PubMed1999

Differences in fat, carbohydrate, and protein metabolism between lean and obese subjects undergoing total starvation.

Despite extensive experimental studies on total starvation, many of the findings relating to protein, fat (plus ketone body), and carbohydrate metabolism remain confusing, although they become more consistent when considered in relation to the degree of initial obesity. During prolonged starvation, protein loss and percent energy derived from protein oxidation are 2- to 3-fold less in the obese than in the lean; percent urine N excreted as urea is 2-fold less in the obese; and the contribution of protein to net glucose production is only about half in the obese compared to lean subjects. During short-term starvation (first few days) the following differences are reported: hyperketonaemia is typically 2-fold greater in lean subjects, but associated with a 2-fold lower uptake of ketone bodies by forearm muscle; glucose tolerance becomes impaired more in lean subjects; and both protein turnover and leucine oxidation increase in the lean, but may show no significant change in the obese. It is no longer acceptable to describe the metabolic response to starvation as a single typical response. The differences between lean and obese subjects have important physiological implications, some of which are of obvious relevance to survival.

Blood Glucose↗
PubMed1999

The effects of enteral tube feeding and parenteral nutrition on appetite sensations and food intake in health and disease.

Enteral tube feeding (ETF) and parenteral nutrition (PN) are unphysiological methods of feeding. They may not elicit the cephalic phase response because part or all of the gastrointestinal tract is bypassed, nutrients are typically given in liquid form by a continuous infusion over many hours and often overnight while patients sleep. Work conducted in animals, healthy subjects and patients suggests that nutrients delivered as ETF or PN are less effective in relieving appetite sensations than food intake. Distressing appetite sensations may even occur despite the provision by artificial nutrition of sufficient nutrients to meet requirements. The energy provided by ETF and PN is largely additional to oral food intake in humans eating ad libitum, although the extent to which this occurs may decrease with time. There is a need to establish ways (e.g. nutritional, pharmacological, psychological) to suppress appetite sensations and food intake when eating is contraindicated, and to enhance them when weaning from artificial nutrition is desirable.

Animals↗
PubMed1999

Physical activity levels in a sample of Oxford school children aged 10-13 years.

OBJECTIVE: To determine physical activity levels (PAL) in children aged between 10 and 13 y. DESIGN: Cross-sectional study of physical activity levels on school days, with and without physical education (PE) lessons and at weekend. Data were collected using self-reported activity diaries. SETTING: The children were recruited from a middle school in Oxford. Basal metabolic rate (BMR) and anthropometry were measured in the school. SUBJECTS: Thirty-eight children (12 boys and 26 girls), aged 10-13 y, returned completed activity diaries. PAL values were calculated by applying physical activity ratios (PAR) to the time spent on each activity. BMR and anthropometry were measured within 20 d of activity diary completion. RESULTS: The mean +/-s.d. (range) PAL values for all children were 1.52+/-0.08 (1.34-1.71), 1. 50+/-0.05 (1.44-1.57) for boys and 1.53+/-0.10 (1.34-1.71) for girls. The lowest PAL value (1.48+/-0.13, mean +/-s.d.) was observed in girls on school days without PE lessons. The lowest PAL value in boys (1.46+/-0.13, mean +/-s.d.) was observed at the weekend. PE lessons made a significant difference to the PAL values for boys (1. 58+/-0.09) and girls (1.60+/-0.12). A wide range of PAL values (1. 20-1.87) was recorded in these children. The total energy expenditure for the boys was slightly lower than the estimated average requirements (EAR) predicted by the Department of Health (8. 71+/-0.96 MJ compared with 8.86 MJ/d) for this age group. The girls had a higher average energy expenditure than the predicted EAR (8. 47+/-1.00 MJ/d compared with 7.885). CONCLUSIONS: The children in this study may be classified as light to moderately active with PAL values ranging from 1.20 to 1.87. The promotion of physical activity in childhood will have beneficial effects for the child and their future wellbeing. Programmes aimed at preventing obesity in children should encourage physical activity as well as promoting appropriate dietary changes.

Adolescent↗
PubMed1999

Assessment of limb muscle and adipose tissue by dual-energy X-ray absorptiometry using magnetic resonance imaging for comparison.

OBJECTIVE: To use magnetic resonance imaging (MRI) to validate estimates of muscle and adipose tissue (AT) in lower limb sections obtained by dual-energy X-ray absorptiometry (DXA) modelling. DESIGN: MRI measurements were used as reference for validating limb muscle and AT estimates obtained by DXA models that assume fat-free soft tissue (FFST) comprised mainly muscle: model A accounted for bone hydration only; model B also applied constants for FFST in bone and skin and fat in muscle and AT; model C was as model B but allowing for variable fat in muscle and AT. SUBJECTS: Healthy men (n = 8) and women (n = 8), ages 41-62y; mean (s.d.) body mass indices (BMIs) of 28.6 (5.4) kg/m2 and 25.1 (5.4) kg/m2, respectively. MEASUREMENTS: MRI scans of the legs and whole body DXA scans were analysed for muscle and AT content of thigh (20 cm) and lower leg (10 cm) sections; 24h creatinine excretion was measured. RESULTS: Model A overestimated thigh muscle volume (MRI mean, 2.3 l) substantially (bias 0.36 l), whereas model B underestimated it by only 2% (bias 0.045 l). Lower leg muscle (MRI mean, 0.6 l) was better predicted using model A (bias 0.04 l, 7% overestimate) than model B (bias 0.1 l, 17% underestimate). The 95% limits of agreement were high for these models (thigh, +/-20%; lower leg, +/-47%). Model C predictions were more discrepant than those of model B. There was generally less agreement between MRI and all DXA models for AT. Measurement variability was generally less for DXA measurements of FFST (coefficient of variation 0.7-1.8%) and fat (0.8-3.3%) than model B estimates of muscle (0.5-2.6%) and AT (3.3-6.8%), respectively. Despite strong relationships between them, muscle mass was overestimated by creatinine excretion with highly variable predictability. CONCLUSION: This study has shown the value of DXA models for assessment of muscle and AT in leg sections, but suggests the need to re-evaluate some of the assumptions upon which they are based.

Absorptiometry, Photon↗
PubMed1999

New techniques in nutritional assessment: body composition methods.

New techniques in air-displacement plethysmography seem to have overcome many of the previous problems of poor reproducibility and validity. These have made body-density measurements available to a larger range of individuals, including children, elderly and sick patients who often have difficulties in being submerged underwater in hydrodensitometry systems. The BOD POD air-displacement system (BOD POD body composition system; Life Measurement Instruments, Concord, CA, USA) is more precise than hydrodensitometry, is simple and rapid to operate (approximately 1 min measurements) and the results agree closely with those of hydrodensitometry (e.g. +/- 3.4% for estimation of body fat). Body line scanners employing the principles of three-dimensional photography are potentially able to measure the surface area and volume of the body and its segments even more rapidly (approximately 10 s), but the validity of the measurements needs to be established. Advances in i.r. spectroscopy and mathematical modelling for calculating the area under the curve have improved precision for measuring enrichment of 2H2O in studies of water dilution (CV 0.1-0.9% within the range of 400-1000 microliters/l) in saliva, plasma and urine. The technique is rapid and compares closely with mass spectrometry (bias 1 (SD 2) %). Advances in bedside bioelectrical-impedance techniques are making possible potential measurements of skinfold thicknesses and limb muscle mass electronically. Preliminary results suggest that the electronic method is more reproducible (intra- and inter-individual reproducibility for measuring skinfold thicknesses) and associated with less bias (+12%), than anthropometry (+40%). In addition to these selected examples, the 'mobility' or transfer of reference methods between centres has made the distinction between reference and bedside or field techniques less distinct than in the past.

Adipose Tissue↗
PubMed1999

The effect of inactivity on dietary intake and energy homeostasis.

Reduced physical activity commonly occurs in patients with disease or chronic disabilities, in the elderly, and in certain patients with obesity. Surprisingly, information on the effect of inactivity on energy homeostasis is scarce and often difficult to interpret. In models of reduced physical activity, such as space flights, bed-rest and confinement, subjects frequently lose weight (< 5%), predominantly in the form of fat-free mass. In some cases this is compensated by an increase in fat mass, which means that changes in weight are poor indicators of energy balance. The extent to which spontaneous reduction in energy intake (in most studies energy intake is fixed) compensates or overcompensates for the reduction in energy expenditure (mainly physical activity and to a small extent in BMR, typically < 6%) is largely underexamined. Preliminary observations suggesting that there is a preferential selection of low-energy-dense foods (low in fat) require confirmation under carefully controlled experimental conditions. It is concluded that a comprehensive and systematic evaluation is needed to address the effects and relevance of various degrees of physical inactivity to energy homeostasis, in relation to disease and space medicine.

Anorexia↗
PubMed1999

Four-component model of body composition in children: density and hydration of fat-free mass and comparison with simpler models.

BACKGROUND: Body composition in children is generally measured by 2-component (2C) models, which are subject to error arising from variation in fat-free mass (FFM) composition. The 4-component (4C) model, which divides body weight into fat, water, mineral, and protein, can overcome these limitations. OBJECTIVE: The aims of our study were to 1) describe 4C model data for children aged 8-12 y; 2) evaluate interindividual variability in the hydration, bone mineral content, and density of FFM; 3) evaluate the success with which 2C models and bedside techniques measure body composition in this age group with use of the 4C model as a reference. DESIGN: Dual-energy X-ray absorptiometry, underwater weighing, deuterium dilution, bioelectrical impedance analysis, and anthropometry were used to determine body composition in 30 children. The contribution of methodologic error to the observed variability in the hydration and density of FFM was evaluated by using propagation of error. RESULTS: Mean (+/-SD) FFM density and hydration were 1.0864+/-0.0074 kg/L and 75.3+/-2.2%, respectively, and were significantly different from adult values (P < 0.02). Relative to the 4C model, deuterium dilution and dual-energy X-ray absorptiometry showed no mean bias for fatness, whereas underwater weighing underestimated fatness (P < 0.025). Fatness determined by using skinfold-thickness and bioelectrical impedance analysis measurements along with published equations showed poor agreement with 4C model data. CONCLUSIONS: Biological variability and methodologic error contribute equally to the variability of FFM composition. Our findings have major implications for bedside prediction methods used for children, traditionally developed in relation to underwater weighing.

Adipose Tissue↗
PubMed1999

Epilepsy and EEG findings in males with fragile X syndrome.

PURPOSE AND METHODS: One hundred and ninety-two fragile X male patients were investigated for seizures and EEG findings, 168 in a retrospective and 24 in another prospective study, to characterize the natural history of seizures, epilepsy, and EEG abnormalities in males with this syndrome. RESULTS: Seizures were documented in 35 (18.2%) of 192 patients; they never started before the age of 2 years or after the age of 9 years. Seizures were frequently of the complex partial type and less frequently of the partial motor and generalized type. Seizures involving frontal and temporal lobes were commonly seen and were usually well controlled by anticonvulsants. In the majority of young fragile X patients studied, an age-related paroxysmal EEG pattern was found, which showed neurophysiologic characteristics very similar to those of the centrotemporal spikes. CONCLUSIONS: These findings confirm that fragile X syndrome can be considered a genetic model of epilepsy.

Adolescent↗